Feline Constipation Flashcards
functions of the colon
- fermentation & nutrient production by colonic flora
- water & electrolyte absorption
- fecal storage
constipation
infrequent, difficult evacuation of dry/hard feces
still productive
obstipation
severe constipation resulting in an inability to defecate
NOT productive
requires medical intervention
megacolon
irreversible colonic dilation following chronic constipation
muscle fibers come apart and can no longer go back together
how is megacolon diagnosed
radiographs
idiopathic megacolon
megacolon with no known underlying cause
diagnosis of exclusion
dyschezia
difficult and painful defecation
tenesmus
feeling of urgency to defecate - manifests as straining
predisposing factors for constipation
- sedentary lifestyle +/- obesity
- history of trauma
- dehydration
- diet - low fiber or high indigestible
- underlying causes - functional vs mechanical
history & PE of constipated patients
history: constipation, tenesmus +/- dyschezia, hematochezia, intermittent diarrhea, hyporexia, weight loss, vomiting
PE:
- distended colon w/ firm feces
- abdominal pain
- +/- dehydration, weight loss, poor BCS, neurologic deficits
what to evaluate on a sedated rectal exam
- pelvic fractures
- stenosis
- colonic foreign bodies
- strictures
- masses
- hernias
functional etiologies of constipation
systemic underlying cause of decreased motility
1. neurologic
2. dehydration
3. severe electrolyte derangements
neurologic constipation
- pelvic trauma
- sacrocaudal luxation (“tail pull”)
- dysautonomia
- ganglionopathy
dehydration related constipation
- systemic disease: CKD, diabetes mellitus, chronic vomiting, neoplasia
- lack of access to water/anorexia
what electrolyte derangements cause constipation
hypokalemia
hypercalcemia
mechanical etiologies of constipation
- intraluminal - abnormal colon
- colorectal masses
- strictures
- atresia ani
- foreign bodies - extraluminal - normal colon
- orthopedic stenosis or fractures
- masses
- pelvic trauma
- deformities
idiopathic megacolon
most common cause of feline obstipation
cause is unknown - suspected disturbance in colonic smooth muscle contraction leading to chronic constipation –> megacolon
diagnostics for functional constipation
- minimum database
- CBC: dehydration
- chem: electrolyte changes or signs of metabolic disease
- USG: high with dehydration, low with CKD - history - trauma?
- neuro exam
- decreased anal tone
- perineal reflex
- paraparesis
diagnostics for mechanical constipation
- sedated rectal
- radiographs
- ultrasound - extraluminal ST masses
- colonoscopy - intraluminal masses
radiographic diagnosis of megacolon
colonic diameter >1.5x width of L5
treatment of obstipation
requires HOSPITALIZATION
- IV fluids
- serial warm water enemas
- monitor electrolytes
- manual deobstipation
- if medical therapies unsuccessful
- performed under anesthesia
medical management for constipation
must first address underlying causes
- diet - high fiber
- stool softeners
- rectal suppositories
- cisapride
- do NOT use metaclopramide - doesn’t work on colon
what medical therapies are contraindicated
human enemas - causes severe electrolyte derangements (hypokalemia, hypernatremia)
do not use mineral oil
surgical management of obstipation
subtotal colectomy - surgical removal of >95% of the colon
only performed after exhausting all medical options in refractory idiopathic cases
